Traditionally, thermodynamic power generation cycles, such as the Brayton cycle, employ an ideal gas, such as atmospheric air. Such cycles are typically open in the sense that after the air flows through the components of the cycle, it is exhausted back to atmosphere at a relatively high temperature so that a considerable amount heat generated by the combustion of fuel is lost from the cycle. A common approach to capturing and utilizing waste heat in a Brayton cycle is to use a recuperator to extract heat from the turbine exhaust gas and transfer it, via a heat exchanger, to the air discharging from the compressor. Since such heat transfer raises the temperature of the air entering the combustor, less fuel is required to achieve the desired turbine inlet temperature. The result is improved thermal efficiencies for the overall thermodynamic cycle. However, even in such recuperated cycles, the thermal efficiency is limited by the fact that the turbine exhaust gas temperature can never be cooled below that of the compressor discharge air, since heat can only flow from a high temperature source to a low temperature sink. More recently, interest has arisen concerning the use of supercritical fluids, such as supercritical carbon dioxide (SCO2), in closed thermodynamic power generation cycles.
A typical thermodynamic power generation cycles that uses supercritical fluids includes compressors, turbines, combustors and heat exchangers arranged in a first Brayton cycle, in which the working fluid is a supercritical fluid, and a second Brayton cycle, in which the working fluid is ambient air. Heat exchangers required to transfer heat between the supercritical fluid cycle and the ambient cycle may be large, expensive, and impractical to implement. More effectively managing flow cycles can improve heat transfer efficiency in power generation systems that employ supercritical fluid cycles.